Question

I’m trying to build a standard compliant website framework which serves XHTML 1.1 as application/xhtml+xml or HTML 4.01 as text/html depending on the browser support. Currently it just looks for “application/xhtml+xml” anywhere in the accept header, and uses that if it exists, but that’s not flexible – text/html might have a higher score. Also, it will become more complex when other formats (WAP, SVG, XForms etc.) are added. So, does anyone know of a tried and tested piece of PHP code to select, from a string array given by the server, either the one best supported by the client or an ordered list based on the client score?

Answer 1

You can leverage apache’s mod_negotiation module. This way you can use the full range of negotiation capabilities the module offers, including your own preferences for the content type (e,g, “I really want to deliver application/xhtml+xml, unless the client very much prefers something else”).
basic solution:

• create a .htaccess file with

  AddHandler type-map .var

  as contents

• create a file foo.var with

  URI: foo
  
  URI: foo.php/html
  Content-type: text/html; qs=0.7
  
  URI: foo.php/xhtml
  Content-type: application/xhtml+xml; qs=0.8

  as contents

• create a file foo.php with

  <?php
  echo 'selected type: ', substr($_SERVER['PATH_INFO'], 1);

  as contents.

• request http://localhost/whatever/foo.var

For this to work you need mod_negotiation enabled, the appropriate AllowOverride privileges for AddHandler and AcceptPathInfo not being disabled for $_SERVER[‘PATH_INFO’].
With my Firefox sending “Accept: text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8″ and the example .var map the result is “selected type: xhtml”.
You can use other “tweaks” to get rid of PATH_INFO or the need to request foo.var, but the basic concept is: let mod_negotiation redirect the request to your php script in a way that the script can “read” the selected content-type.

So, does anyone know of a tried and tested piece of PHP code to select

It’s not a pure php solution but I’d say mod_negotiation has been tried and tested 😉